Rehabilitating underground pipes with expanding helically wound liner

ABSTRACT

A method of rehabilitating underground pipes which comprises the steps of: (a) forming a liner pipe (5) by winding a strip (4) made of a synthetic resin into a helical shape so that the side edges of the convolutions of the wound strip (4) are interengaged with each other; (b) continuously introducing the liner pipe (5) into an underground pipe (1) while the liner pipe (5) is being advanced inside the underground pipe (1); inserting a slip restraining member in the form of a wire rod (6) continuously to the interconnected edges of the convolutions of the said strip (4), and then removing the said strip (4) when the diameter of said liner pipe (5) is to be increased at the same rate as said strip (4) for forming said helical liner pipe (5) is conveyed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of rehabilitating underground pipeswith a lining comprising a helically wound liner pipe made of asynthetic resin, this comprises the steps of winding a strip of asynthetic resin into a helical shape around a virtual cylinder, so thatthe side edges of the wound strip are interengaged with each other, andcontinuously introducing the helically wound liner pipe hereafterreferred to as a "liner pipe", into an underground pipe while the linerpipe is being advanced inside the underground pipe, and then fixing theleading end of the liner pipe to the underground pipe and furtheradvancing the liner pipe being formed inside the underground pipe sothat the wound strip is allowed to slide around the virtual cylinderwith is side edges still interengaged with each other to result in agradual progressive increase in the diameter of the liner piper towardthe winding machine end.

2. Description of the Related Art

The method of forming such helical pipes has already been disclosed inPatent literature, see for instance European Patent Office PublicationNo. 0001894 in the name of Ri Loc Hong Kong Limited, or PatentCo-operation Treaty Publication No. WO85/03755 in the name of Rib LocHong Kong Limited which related to a modification of the system, and seeparticularly Patent Co-operation Treaty Publication No. WO89/01588 inthe name of Rib Loc Australia Pty. Ltd. which related to restrainingmeans for such a pipe structure to control the progressive expansion ofthe helically wound liner pipe in the underground pipe.

SUMMARY OF THE INVENTION

Thus according to the described method of rehabilitating undergroundpipes with a lining formed of a helically wound liner piper made of asynthetic resin, the liner pipe has a comparatively small diameter whenbeing introduced into the underground pipe because the interconnectedside edges of the convolutions of the wound strip are securely engagedwith each other by use of a wire rod, so that it can smoothly advanceinside the underground pipe without being disturbed by frictionalresistance, which would be exerted by the inner surface of theunderground pipe on the helical liner pipe.

After the liner piper is introduced into the underground pipe and theleading end of the helical liner pipe is fixed to the underground pipe,the restraining member is removed from the strip, bringing about theslackening of the engagement between the interengaged side edges of thewound strip, so that the wound strip slides around a virtual cylinder,resulting in a increase in diameter of the liner pipe.

Consequently, the outer diameter of the liner piper is madesubstantially equal to the inner diameter of the underground pipe; andthe cross-sectional area of the underground pipe with the lining formedby the liner pipe is substantially equal to that of the underground pipewithout the lining, so that the amount of a fluid which flows throughthe pipe with the lining per unit minute is substantially equal to oreven greater than that which flows through the pipe without the liningper unit minute, depending on the type of the underground pipe to berehabilitated.

Because the sliding of the wound strip around a virtual cylinder isphysically prevented by the restraining member, the formation of theliner pipe can be performed without difficulty even when the liner pipegets wet inside sewage pipes or during rainy weather.

The present invention relates generally to the described system but isspecifically directed to further improvements, particularly a methodwhich allows the space between the expanding pipe to be filled byinjecting a backfilling material into the space between the outersurface of the liner piper and the inner surface of the undergroundpipe, the method consisting of moving a unit for supplying thebackfilling material in the direction of the axis of the liner pipe asthe portion of the said liner pipe with the increasing diameter is movedin the same direction.

The backfilling material is applied onto the outer surface of the linerpipe directly after the diameter of the liner pipe is increased, so thatthe efficiency in performing the work is substantially increased. When afoaming material is used for backfilling, the space between the innersurface of the underground pipe and the outer surface of the liner pipercan be filled without fail. Moreover, the rate at which the restrainingmember is removed from the strip, the rate at which the unit forsupplying the backfilling material is moved, and the rate at which thebackfilling material is supplied are controlled, based on the rate atwhich the strip is conveyed, efficiency in performing the work is muchincreased and the number of persons needed to carry out the work can bereduced to a great extent.

The method of forming the restraining means between the edges of theconvolutions of the strip and the application thereof also forms part ofthis invention as well as the particular backfilling material.

Other features of the present invention will be apparent from thefollowing description which is made with reference to the accompanyingdrawings which are of an illustrative nature only and not necessarily tobe taken as limiting the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a longitudinal section of an underground pipe showing asection of liner pipe according to this invention inserted in theunderground pipe between manholes with part of the liner pipe beingshown expanded.

FIG. 2 is a similar view to FIG. 1 but showing the liner pipe beforeexpansion has taken place to show the smaller diameter which allowsinsertion during the formation and forward projection of the liner pipeby the winding machine.

FIG. 3 is a typical form of the strip and joining means used accordingto this invention, the illustration showing a cross section of the stripinvolved and showing how the two edges of adjacent convolutions arejoined together.

FIG. 4 is a transverse section of the two edges joined together andlocked against longitudinal movement, the one in relation to the other,by a wire rod which expands the inner part of the join into a lockingconfiguration and forces the locking member to restrict sliding actionbetween the inter engaged edges of the convolutions of the strip.

FIG. 5 is a view, to reduced scale, of the end of a helically woundliner pipe showing how the locking wire rod is fed into the joiningmember of the strip as the liner pipe is being formed.

FIG. 6 is a longitudinal section showing how during the formation andexpansion of the liner pipe the wire rod is fed into position andwithdrawn at the point where expansion proceeds in a progressive manner.

FIG. 7 is a fragmentary side elevation of guide means for the wire rodwhich ensure that the wire rod is pulled cleanly out of the groove inwhich it is housed, the guide member moving around within the helicallywound liner pipe which is being expanded according to the position atwhich the wire rod is being removed.

FIG. 8 is a perspective view showing the injection device used whereback filling material, in this case a foaming material, is injected tothe area where expansion of the helically wound pipe is taking place.

FIG. 9 is a similar view to FIG. 8 but showing the form of the injectingdevice when injection of a material other than a foaming material isrequired, and

FIG. 10 is a schematic view showing the system in use, the undergroundpipe and the helically wound liner pipe being shown in longitudinalsection to show particularly the wire rod and the back fill injectionsystem.

The underground pipe 1 has manholes 2 at intervals and in one of theseis positioned a winding machine 3 by means of which a strip 4 is formedinto a helically wound liner pipe 5 which is advanced into theunderground pipe 1 as it is being formed. When the advancing end of thehelically wound liner pipe 5 reaches the next manhole 2, the liner pipe5 is expanded by rotating the end of the liner pipe until it engages theunderground pipe 1 and is fixed thereto, after which further productionof the liner pipe 5 by the winding machine 3 causes progressiveexpansion of the liner pipe 5 as shown more particularly in FIG. 1, theexpansion being controlled by unlocking the join formed betweenconvolutions of the strip by withdrawing the wire rod 6 which is forcedinto the join between convolutions of the strip to lock the join againstsliding motion of one edge over the other, the wire rod 6 being fed froma spool 7 and after withdrawal from the liner pipe 5 at the point ofrequired expansion is taken up on a second spool 8.

The locking action is described particularly with reference to FIGS. 3 4and 5 where the strip 4 is shown as having a number of upstanding ribs 9and at one end, a socket 10 adapted to engage a hollow bead 11 which isshaped to fit into the socket 10 with a sliding fit when not locked bythe wire rod 6, such a sliding joint being shown at 12 in FIG. 3.

In FIG. 4 the wire rod 6 is shown in position, the dimensions of thisbeing such that the bead 11 is expanded tightly into the socket 10 sothat when the wire is in position during initial winding no expansion ofthe liner pipe 5 can take place, expansion being only allowed after therequired length of liner pipe 5 has been inserted into the undergroundpipe 1 and its distant end expanded and fixed.

FIG. 6 illustrates how the wire rod 6 is fed from the first spool 7 overguides 13 into the hollow of the bead 11, a guide 14 being used whichmay be adapted to deform the wire rod 6 to enhance slip preventionbetween the socket 10 and the bead 11 of the strip 4.

In FIG. 6 is shown particularly how the wire rod 6 passes from the firstspool through the guide 14 to be wound into the hollow in the bead 11and is drawn from the formed liner pipe 5 through a reel 15 which may befree to move within the liner pipe 5 but has a belled end 16 to allowthe wire rod 6 to pass through it and be guided towards the area at theliner pipe where it is to be withdrawn, this reel having cheeks 17 whichallow it to accommodate itself and follow the path of the wire rod 6 asit is withdrawn. FIG. 6 showing only diagrammatically the staticposition of the reel which can roll around in the liner pipe 5 accordingto where the wire rod 6 is being withdrawn from the hollow of the beadas the expanding proceeds.

In FIG. 5 is shown ejection means 18 used when a two component back fillmaterial is used, the injection means 18 having two supply pipes 19 and20 connected together in a mixing chamber 21 which feeds the mixedfoaming backfill material through the nozzle 22.

In FIG. 9 the injection means 18 have only a single supply pipe 23feeding the injection nozzle 22, and the injection means in this caseinclude brackets 24 which support the nozzle 22 and which can engagetracks or guide rods which can hold the nozzle 22 above the area intowhich the backfilling material is to be discharged.

Referring to FIG. 10, this shows control means 26 for synchronizing thevarious actions which occur during the helical winding of the strip 4into the liner pipe 5, the expansion of the liner pipe 5 byprogressively withdrawing the wire rod 6 from the hollow head 11 and thesupply of the backfilling material and controlling the point of backfillthrough the nozzle 22 by moving the nozzle 22 synchronously with thewithdrawal of the wire rod 6 to ensure that the backfill is applied atthe location where the liner pip 5 is about to contact the undergroundpipe 1.

As said the back filling material is preferably a foaming material whichsets after the line pipe 5 is in its fully expanded position but otherform of backfill material can be used such as a cementitious material orgrouting which can be applied from the nozzle 22 into the area where thematerial is required or can be forced into the spaced between the ribson the strip 4.

The control means 26 are connected to secure and control the windingmachine 3 as well as actuating the means 27 which withdraw the wire rod6 and the means 28 which withdraw the nozzle 22 synchronously with thewithdrawal of the wire rod 6, the driving means which effect the actualwithdrawal of the wire rod being shown schematically by the rollers 29,while the driving means which move the nozzle 22 are shown schematicallyby the roller 30. The means 27 and 28 can be hydraulic motors or similarspeed controllable units.

We claim:
 1. A method of rehabilitating underground pipes (1) using alining consisting of a helically formed liner pipe (5) made of asynthetic resin, which comprises the steps of: (a) forming a liner piper(5) by winding a strip (4) made of a synthetic resin into a helicalshape around a virtual cylinder, so that the side edges of theconvolutions of the wound strip (4) are interengaged with each other;inserting a slip restraining member in the form of a wire rod (6)continuously to the interconnected edges of the convolutions of the saidstrip (4), and then removing the said strip (4) when the diameter ofsaid liner pipe (5) is to be increased at the same rate as said strip94) for forming said helical liner pipe (5) is conveyed; (b)continuously introducing said liner pipe (5) into an underground pipe(1) while said liner pipe (5) is being advanced inside the undergroundpipe (1); (c) fixing the leading end of said liner pipe (5) to theunderground pipe when a required length has been advanced; (d) furtheradvancing said liner pipe (5) inside the underground pipe (1) with itsleading end fixed to the underground pie (1), so that the wound strip(4) is allowed to slide around the virtual cylinder with its side edgesstill being interengaged with each other, resulting in the gradualincrease in the diameter of said helical liner pipe; and (e) injecting abackfilling material into the space between the outer surface of saidliner pipe (5) and the inner surface of the said underground pipe (1) bymoving a nozzle (22) for supplying the backfilling material in thedirection of the axis of said liner pie (5) synchronously as said rod iswithdrawn and the increasing diameter is shifted in the same direction.2. The method of rehabilitating underground pipes (1) with a liner pipe(5) formed from a strip (4) of synthetic seam according to claim 1wherein the backfilling material is a foaming material.